Solanum americanum

Solanum americanum, the American nightshade, is a herbaceous flowering plant native to the Americas, from the south and west of the United States south to Paraguay and Peru; it also occurs in Hawaii, where it is considered possibly indigenous or may be a Polynesian introduction. It is used as a medicinal in Cameroon, Kenya, Hawaii, Panama, Sierra Leone, and Tanzania, and as a wild or cultivated pot herb in Cameroon, Ghana, Guatemala, Kenya, Madagascar, Mauritius, Hawaii and other Pacific Islands, Nigeria, Papua New Guinea, Peru, Sierra Leone, the Seychelles, South Africa, Tanzania, and Uganda.

Additional recommended knowledge

Essential Laboratory Skills Guide

Daily Sensitivity Test

Correct Test Weight Handling Guide: 12 Practical Tips

It grows up to 1-1.5 m tall and is an annual or short-lived perennial. The leaves are alternate on the branch, and vary greatly in size, up to 10 cm long and 7 cm broad, with a 4 cm petiole and a coarsely wavy or toothed margin. The flowers are about 1 cm diameter, white or occasionally light purple, with yellow stamens. The fruit is a shiny black berry 5-10 mm diameter, containing numerous small seeds; when mature they should be considered poisonous as they may contain high levels of solanine. Also, the plant is easily confused with truly poisonous nightshades.

Identification

American nightshade can be confused with a variety of other related nightshades. Here is a quick guide for differentiating between species.

American nightshade Solanum americanum

The underside of its hairy leaves is not reddish-purple. The berries are speckled with white until it is fully ripe and turns black.

Black nightshade Solanum nigrum

Berries are purple or dark green and dull. They are almost completely exposed (very small calyx).

Eastern black nightshade Solanum ptycanthum

The underside of the leaves is reddish purple and the berries are dark.

Hairy nightshade Solanum villosum

Berries are light green or yellow when ripe and the leaves are so hairy that they may feel sticky.

References

• Missouriplants: Solanum americanum (numerous photos, detailed description)
• Germplasm Resources Information Network: Solanum americanum
• Pacific Island Ecosystems at Risk: Solanum americanum (very detailed description)
• Identifying nighshades as weeds
• Edmonds, J. M. & J. A. Chweya, 1997: Black nightshades, Solanum nigrum L., and related species. Promoting the conservation and use of underutilized and neglected crops 15. - IPGRI/IPK, Rome/Gatersleben 113 pp
• Solanum americanum Mill. on Solanaceae Source - Images, specimens and a full list of scientific synonyms. Full descriptions and identification keys coming soon!